AVS 47th International Symposium
    Processing at the Nanoscale/NANO 6 Thursday Sessions
       Session NS+NANO6+MC-ThA

Paper NS+NANO6+MC-ThA8
Silicon Nanostructures via Intense Ultrafast Electronic Excitation

Thursday, October 5, 2000, 4:20 pm, Room 302

Session: Near-field Optics and Photonics
Presenter: A.V. Hamza, University of California, Lawrence Livermore National Laboratory
Authors: A.V. Hamza, University of California, Lawrence Livermore National Laboratory
M.W. Newman, University of California, Lawrence Livermore National Laboratory
T. Schenkel, University of California, Lawrence Berkeley National Laboratory
H.W.H. Lee, University of California, Lawrence Livermore National Laboratory
P. Thielen, University of California, Lawrence Livermore National laboratory
J.W. McDonald, University of California, Lawrence Livermore National Laboratory
D.H. Schneider, University of California, Lawrence Livermore National Laboratory
Correspondent: Click to Email
Due to the indirect nature of its band gap, bulk silicon is typically a poor photon emitter upon external excitation. However, as the crystal size approaches nanometer scales, the band gap widens due to quantum confinement and may become direct allowing for more efficient photon emission. Phase transformations induced by intense, ultrafast electronic excitation from slow, highly charged ions have produced nanometer-sized structures in silicon. Beams of highly charged ions of various charge state from 20+ to 69+ and various kinetic energies from 5 to 14 keV times charge have been utilized to induce this phase transformation in clean, silicon surfaces. The new phase is characterized by ex situ photoluminescence from the irradiated area after excitation with laser wavelengths from 379 - 514 nm. Photoluminescence spectra from the exposed areas show emission centered at ~540 nm. This is consistent with emission observed from 1-2 nm silicon nanocrystals. A series of sharp lines at 565, 555, and 548 nm are present in the photoluminescence spectrum from areas exposed to Xe@super 44+@ which are characteristic of an excitonic series in nanometer-sized material.